As far as I am aware, Canon have only made one statement as to the damage itself, that was corrosion around the shutter release button, ergo, water has come in via this port. From the information ‘Martin’ has provided, there was light rain, a Kata bag was used and the shutter released inside the bag without gloves being worn. The problem also occurred before being returned to a warm cabin, so condensation here is not relevant.
Now I’m speculating. Water and salt must have got in via the finger when releasing the shutter. Is this because of slightly damp hands due to the conditions or can condensation form when warm hands meet a cold object? (I’d have probably had my hands in an out of my pockets trying to keep them warm) Whilst I am framing up I have my finger resting on the shutter release button for some time generally.
Do rain proof covers exacerbate the situation as somebody else suggested? I don’t know, but they must deprive the camera of any airflow (Condensation is encouraged by poor air circulation).
I am a 5D Mark 2 user, I am not being critical I hope, I am trying to find a workable solution for myself. If the camera is on a tripod, I myself will use a cable release, is it feasible to fire the shutter from the ‘outside’ of any raincover on the camera?? Thuswise keeping the shutter finger away.
As far as moving from a cold to a warm climate and condensation appearing, does it make any difference whether a ‘ziplock’ bag is used or is a general camera bag ok?? I’d appreciate opinions on this one – I have read some others being ok with the camera bag – is this something else to cart around, large ziplock bags.
I'm not sure I'm happy with the faulty batch scenario - although I wish it were true.